Modeling of the saturation current of a fission chamber taking into account the distorsion of electric field due to space charge effects

Fission chambers were first made fifty years ago for neutron detection. At the moment, the French Atomic Energy Commission \textsf{(CEA-Cadarache)} is developing a sub-miniature fission chamber technology with a diameter of 1.5 mm working in the current mode (Bign). To be able to measure intense fluxes, it is necessary to adjust the chamber geometry and the gas pressure before testing it under real neutron flux. In the present paper, we describe a theoretical method to foresee the current-voltage characteristics (sensitivity and saturation plateau) of a fission chamber whose geometrical features are given, taking into account the neutron flux to be measured (spectrum and intensity). The proposed theoretical model describes electric field distortion resulting from charge collection effect. A computer code has been developed on this model basis. Its application to 3 kinds of fission chambers indicates excellent agreement between theoretical model and measured characteristics

Les relacions transpirinenques a la Catalunya Moderna: els tractats de "Lligues i Patzeries"

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Communication and division on the northern border of Catalonia between the 15th and 18th centuries

International audienceCatalonia's northern border underwent major shifts during the Modern Age. Wars played a significant role in these changes, as evi-denced by the Treaty of the Pyrenees in 1659, a stage in the process which led to the creation of an actual state borderline that the people gradually started to internalise. Nonetheless, the border dwellers still interacted with each other, making it a place of intense exchanges which included them within a larger cultural and economic framework in which they strove to live "as good neighbours", as they themselves put it

La frontera pirinenca i el comerç a l'època moderna

Análisi del comerç en la frontera pirinenca durant l'època moderna. S'analitzen els acords de lliure comerç i els seus obstacles, les xarxes comercials a través dels Pirineus, la incidència de la guerra en el comerç i es focaliza en la zona de Foix com a exemple concret d'eix comercial.Estudio del comercio en la frontera pirinaica durante la época moderna. Se analizan los acuerdos de libre comercio y sus travas, las redes comerciales a través de los Pirineos, la incidencia de la guerra en el comercio y se focaliza en la zona de Foix como ejemplo concreto de eje comercial.This article analizes trade in the Pyrenees borderland during the early modern age. The author focuses on the covenants for commercial freedom and their obstacles, the commercial nets through the Pyrenees, the war incidence on trade and the example of the region of Foix as a place for the development of commercial axis

Growth rate of Rayleigh-Taylor turbulent mixing layers with the foliation approach

For years, astrophysicists, plasma fusion and fluid physicists have puzzled over Rayleigh-Taylor turbulent mixing layers. In particular, strong discrepancies in the growth rates have been observed between experiments and numerical simulations. Although two phenomenological mechanisms (mode-coupling and mode-competition) have brought some insight on these differences, convincing theoretical arguments are missing to explain the observed values. In this paper, we provide an analytical expression of the growth rate compatible with both mechanisms and is valide for a self-similar, low Atwood Rayleigh-Taylor turbulent mixing subjected to a constant or time-varying acceleration. The key step in this work is the introduction of {\it foliated} averages and {\it foliated} turbulent spectra highlighted in our three dimensional numerical simulations. We show that the exact value of the Rayleigh-Taylor growth rate not only depends upon the acceleration history but is also bound to the power-law exponent of the {\it foliated} spectra at large scales

La correcte exécution d’un plan de continuation n’empêche pas de prendre une mesure conservatoire à l’encontre de l’associé de la société redressée (Note sous Com. 25 mars 2020, no 18-17.924 FS-P+B)

Si l’utilité d’une mesure conservatoire en cas de procédure collective est évidente, comme en témoigne l’abondant contentieux relatif à la faculté pour un créancier de prendre de telles dispositions sur le patrimoine du garant d’une société débitrice en plan, son régime méritait encore d’être précisé à l’endroit des associés d’une société civile immobilière. Tel est l’objet de l’arrêt rapporté